A fluorine-containing elastomer consisting of a copolymer such as a copolymer from vinylidene fluoride and another fluorine-containing monomer is an elastomer excellent in heat resistance and is chemical resistance, and used for various sealing materials or packings.
In recent years, further, a fluorine-containing elastomer has been incorporated into a thermoplastic resin to improve the impact resistance of thermoplastic resins. For example, JP-A-3-263460 discloses an impact-resistant resin composition obtained by incorporating a fluorine-containing elastomer into a polycyanoaryl ether-based resin which is a heat-resistant thermoplastic resin.
As described in the above JP-A-3-263460, however, when a fluorine-containing elastomer is incorporated into a thermoplastic resin, the effect on the improvement in impact resistance is not sufficient although the impact resistance is improved. That is, since the fluorine-containing elastomer has low surface energy and poor wettability to the thermoplastic resin, the compatibility (miscibility) of the fluorine-containing elastomer with the thermoplastic resin is insufficient and the advantage of the fluorine-containing elastomer as an agent for imparting impact resistance cannot be sufficiently worked.
Further, when exposed to a high temperature, the fluorine-containing elastomer is partially decomposed to generate hydrogen fluoride, a strong acid. Therefore, it also has a defect in that a thermoplastic resin composition containing the fluorine-containing elastomer is inferior in heat resistance. As a method for preventing the generation of hydrogen fluoride caused by the decomposition of the fluorine-containing elastomer, JP-A-55-16057 discloses a method in which an amine-containing antioxidant is incorporated into the fluorine-containing elastomer. In view of cost, however, it is not expedient to improve the heat resistance by adding an amine-containing antioxidant to a composition of a thermoplastic resin and a fluorine-containing elastomer, since it increases the number of components which constitute the resin composition. Further, for some intended resin molded articles, it is not undesirable to incorporate an amine-containing antioxidant.
Although the generation of hydrogen fluoride could be prevented by adding an amine-containing antioxidant, it is not possible to expect an effect on the improvement in the impact resistance in all cases.